Plasma processing apparatuses are used to process semiconductor substrates by techniques including etching, physical vapor deposition (PVD), chemical vapor deposition (CVD), and resist removal. One type of plasma processing apparatus used in plasma processing includes a reaction chamber containing top and bottom electrodes. A radio frequency (RF) power is applied between the electrodes to excite a process gas into a plasma for processing semiconductor substrates in the reaction chamber.
One challenge facing designers of plasma processing chambers is that the plasma etch conditions create significant ion bombardment of the surfaces of the processing chamber that are exposed to the plasma. This ion bombardment, combined with plasma chemistries and/or etch byproducts, can produce significant erosion, corrosion and corrosion-erosion of the plasma-exposed surfaces of the processing chamber. Another challenge is to control heat transfer across a bottom electrode assembly and a semiconductor substrate (e.g., silicon substrate), in particular, to make the temperature at the center of the substrate equal to the temperature at the edge of the substrate, or alternatively, to make a desired temperature profile across the substrate. To alleviate such challenges, an edge ring assembly is implemented, fitting around the substrate.